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#include "TOTP.h"
#include "sha1.h"
#include "sha256.h"
#include "sha512.h"
#include <stdio.h>
uint8_t* _hmacKey;
uint8_t _keyLength;
uint8_t _timeZoneOffset;
uint32_t _timeStep;
hmac_alg _algorithm;
// Init the library with the private key, its length, the timeStep duration and the algorithm that should be used
void TOTP(uint8_t* hmacKey, uint8_t keyLength, uint32_t timeStep, hmac_alg algorithm) {
_hmacKey = hmacKey;
_keyLength = keyLength;
_timeStep = timeStep;
_algorithm = algorithm;
}
void setTimezone(uint8_t timezone){
_timeZoneOffset = timezone;
}
static uint32_t TimeStruct2Timestamp(struct tm time){
//time.tm_mon -= 1;
//time.tm_year -= 1900;
return mktime(&(time)) - (_timeZoneOffset * 3600) - 2208988800;
}
// Generate a code, using the timestamp provided
uint32_t getCodeFromTimestamp(uint32_t timeStamp) {
uint32_t steps = timeStamp / _timeStep;
return getCodeFromSteps(steps);
}
// Generate a code, using the timestamp provided
uint32_t getCodeFromTimeStruct(struct tm time) {
return getCodeFromTimestamp(TimeStruct2Timestamp(time));
}
// Generate a code, using the number of steps provided
uint32_t getCodeFromSteps(uint32_t steps) {
// STEP 0, map the number of steps in a 8-bytes array (counter value)
uint8_t _byteArray[8];
_byteArray[0] = 0x00;
_byteArray[1] = 0x00;
_byteArray[2] = 0x00;
_byteArray[3] = 0x00;
_byteArray[4] = (uint8_t)((steps >> 24) & 0xFF);
_byteArray[5] = (uint8_t)((steps >> 16) & 0xFF);
_byteArray[6] = (uint8_t)((steps >> 8) & 0XFF);
_byteArray[7] = (uint8_t)((steps & 0XFF));
switch(_algorithm){
case SHA1:
return(TOTP_HMAC_SHA1(_hmacKey, _keyLength, _byteArray, 8));
case SHA224:
return(TOTP_HMAC_SHA256(_hmacKey, _keyLength, _byteArray, 8, 1));
case SHA256:
return(TOTP_HMAC_SHA256(_hmacKey, _keyLength, _byteArray, 8, 0));
case SHA384:
return(TOTP_HMAC_SHA512(_hmacKey, _keyLength, _byteArray, 8, 1));
case SHA512:
return(TOTP_HMAC_SHA512(_hmacKey, _keyLength, _byteArray, 8, 0));
default:
return(0);
}
}
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